Pilot for flare stack



April 26, 1966 R. D. REED I PILOT FOR FLARE STACK Filed Sept. 5, 1963 INVENTOR ROBERT D. RE'EW F/GJ ATTGRNEY United States Patent 3,247,885 PTLOT Fflll; FLARE STACK Robert ID. Reed, Tulsa, Ulrla, assignor to John Zink Company, Tulsa, Okla, a corporation of Delaware Filed Sept. 5, 1963, Ser. No. 306,844 3 Claims. (Cl. 158-99) The present invention pertains to a burner for gaseous fuel and more particularly pertains to structure which pro- Vides for mixing gas supplied at low pressures with air in such a manner that the mixture moves in one general direction to induce additional air to move into the presence of the burning fuel whereby the mixture burns stably to provide a pilot type burner for kindling gas escaping through the upper end of a flare stack and to provide a pilot type burner which is stable in operation at significant elevations above the surrounding terrain and maintains ignition of the flare stack.

It is a practice in industries where hydrocarbons and other inflammable materals are processed to dispose of some of the gaseous materials by burning. The combination of such gases is desirably carried out in the atmosphere and at significant elevations above grade levels and at the top of a flare stack. Wind currents and other weather conditions tend to make it difficult to maintain ignition of the gases at the upper end of such stacks. Pilot type burners have been employed for such purposes and the structure disclosed in Zink Patent 2,869,631 functions satisfactorily when the gas supplied to the pilot burner has a pressure of one pound or more per square inch. Gas supplied at such pressures are not always available at the location of the flare stack.

It is an object of the present invention to provide a gaseous fuel burner providing stable operation when supported in elevated positions to provide a reliable pilot for a flare stack when gas for the pilot is available at pressures ranging from about two ounces to about ten ounces per square inch.

A more specific object of the invention is to provide structure which forms an annular chamber for receiving a gaseous fuel disposed about a mixing chamber into which the fuel is discharged in such a manner as to provide an energy resultant of the discharging gas with the structure guiding air into a position to be drawn into the presence of the gas to provide a gaseous fuel mixture which moves in one general direction to induce additional limited quantities of air to move into the combustion chamber and provide a flame of the burning fuel mixture which is sufficiently stable to provide a reliable pilot burner for a flare stack.

Other and further objects and features of the invention.

will be appreciated and become apparent to those skilled in the art as the disclosure proceeds and upon consideration of the accompanying drawing and the following detailed description wherein an embodiment of the invention is disclosed.

In the drawing:

FIG. 1 is a fragmentary side elevational view of the upper end portion of a flare. stack illustrating a pilot 'burner assembly embodying invention in association therewith.

FIG. 2 is a view on a larger scale illustrating portions of the pilot burner structure in section.

FIG. 3 is a transverse sectional view taken on the line 3-3 of FIG. 2.

FIG. 4 is another transverse sectional view taken on the line l4- of FIG. 2.

Referring to the drawing there is shown at a flare stack which serves to guide dump gas to a position in the atmosphere for release at the desired elevation. The flare stack is equipped with a tip structure providing for the combustion of the waste gas as it escapes through the $247,885 Patented Apr. 26, 1966 upper open end 11. The flare stack 10 is supported to maintain its axis 12 in a substantially vertical position and the burner tip structure is preferably arranged in a substantially horizontal plane 14.

The burner structure is indicated generally at 16 and is desirably of tubular formation and adapted to be supported adjacent the upper end of the flare stack 10. The tubular shaped structure is oriented so as to discharge burning fuel and a flame angularly over the upper end 11 of the flare stack 10. The burner structure includes a tube 18 which has its axis 19 inclined to the axis 12 of the flare stack at an angle of approximately sixty-three degrees. An air pipe 21 is attached to the lower endof the tube 18 as shown in FIGS. 1 and 2. The axis 19 of the tube 18 is desirably disposed at an angle of approximately one hundred and fifty-three degrees with respect to the axis 22 of the air pipe 21. Such a juncture provides that the pipe 21 depends from the tube 18 with the axis of the pipe 22 in a substantally vertical position and parallel to the flare stack 10. The pipe 21 is carried by a. bracket 23 supported by the flare stack 10. The air pipe 21 depends along the side of the flare stack and desirably has a length of at least ten feet in the portion depending below the tube 18. The lower end 24- of the air tube 21 is open to the atmosphere. The tube 21 having such a length provides the result of the air within the tube 21 being free of any products of combustion taking place at the upper end of the flare stack 10 particularly when the wind is in such a direction that the pilot is at the downwind side of flare stack 10. Clean unpolluted air at atmospheric pressure is thus available Within the pipe 21.

A tubular member 26 is mounted within the lower portion of the tube 18. The tubular member 26 is of smaller diameter than the tube 18 and flanges 27 and 28 carried by the ends of the tubular members 26 join the inner circumference of the tube 18. An annular chamber 29 is thus provided by the interior of the tube 18 and the exterior of the tubular member 26. Gas under pressure of about two ounces to approximately ten ounces per square inch is supplied into the annular chamber 29 through a supply pipe 3d. The pipe 30 may be supported by the bracket 23. The gas supply pipe 30 extends to a source of gas which may be available at a grade level.

A row of ports 31 are provided in the tubular member 26 providing communication from the annular chamber 29 to the interior of the tubular member 26. The ports 31 are circumferentially spaced from each other. The axes of the ports 31 are at an acute angle with respect to the axis 19 and these axes converge upwardly within the tubular member 26. The ports 31 are so disposed that the gas moving from the annular chamber 29 into the interior of the tubular member 26 intermingle along the axis 19 and develop a movement of gas in a downstream direction along the axis 19 to provide an energy resultant in the direction of the arrow 33. The movement of the gas through the ports 31 sets up a pressure less than at rnospheric within the tubular member 26 and in a zone adjacent the ports 31. This lower pressure serves to draw airinto the interior of the tubular member 26 from the pipe 21. This air with the gas flowing from the ports 31 and the resulting gas and air mixture moves in the direction of the arrow 33.

The tube 18 immediately above the upper end of .the tubular member 26 is provided with a plurality of apertures 36 which are circumferentially spaced from each other and in the embodiment illustrated eight of such apertures are provided. The apertures 36 are circumferentially spaced and may be arranged in two rows as shown in FIG. 2. The mixture of gas and air moving in the direction of the arrow 33 as a consequence of the en- 3 ergy resultant develops a significant velocity adjacent the upper end of the chamber within the tubular member 26. This movement of the fuel mixture develops a low pressure zone within the .tube 18 adjacent .the apertures 36 and air enters through the apertures 36. The air mixed with the gas and supplied by the pipe '21 plus the air which enters through the apertures 36 provide ample air for the combustion of the gaseous fuel. A flame is thus developed which has a shape approximating that shown in FIG. 2. The flame issues from the upper end of the tube 18 and is elongated in the direction of the axis 19. The flame and the hot gases are directed over the upper end 11 of the flare stack 10.

The upper end of the tube 18 is chamfered as shown in FIGS. 1 and 2. The plane defining the end surface 38 of the tube 18 is desirably at an angle of approximately sixty-three degrees with respect to the axis 19. The end surface of the tube 18 is thus substantially horizontal and coincides with the plane 14 defining the upper end of the flare stack 10. The chamfered upper end of the tube 18 provides the advantage that there is no obstruction to the flow of wind induced air currents across the upper end of the tube 18 to disturb combustion of the gaseous fuel. If the upper end of the tube 18 were disposed at right angles to the axis 19 there would be a tendency for wind developed air to act in a direction opposite to the movement of the flame and if the static head of the wind should become equal .to the static head of the flame it would impair projection of the flame beyond the end of the tube 18.

Ignition of gas and air mixture within the tube 18 may be initiated by a flame front system which includes a pipe 41 in open communication with the upper end of the .tube 18. The pipe 41 is desirably supported by the bracket 23 and may extend to grade level. The pipe 41 is adapted to be filled with a stoichiometric mixture of gas and air which may be ignited in any suitable manner. The flame front moving through the pipe 41 serves to ignite the fuel mixture within the tube 18.

The annular chamber 29 provides for the storage for a quantity of gas under relatively low pressure which is released through the ports 31 into the interior of the tubular member 26. The released gas moves in directions to cause air to be drawn from the pipe 21 into the chamber Within the tubular member 2-6 and to be mixed with the gas. As the gaseous fuel mixture moves forward and upon ignition provides a flame which serves to kindle the dump gas escaping from the flare stack 10. The air drawn inwardly through the apertures 36 provides for combustion of the fuel mixture and stable operation. The flame escaping through the upper end of .the tube 18 burns during various weather conditions with air currents traversing the upper end of the flare stack 10.

While the invention has been described with reference to specific structural features and with regard to a particular means for igniting the pilot burner various changes may be made. The gaseous fuel burner may be employed for purposes other than serving as a pilot for a flare stack. Such modifications and others may be made without departing from the spirit and scope of the invention as set forth in the appended claims.

What I claim and desire to secure by Letters Patent is:

1. The combination of a pilot burner and a flare stack comprising, a flare stack, a generally erect tube adjacent the upper end of said stack, a pipe in communication with and depending from said tube and having an open lower end disposed below the upper end of said stack, a tubular member within said tube providing an annular space between the interior of the tube and the exterior of the tubular member, means for guiding gas under pressure into said annular space, said tubular member hav-' ing a plurality of circumferentially spaced ports therethrough with their axes converging downstream and towards the axis of said tubular member whereby the gas jets moving therethrough mingle providing an energy resultant moving upwardly within the tubular member providing a lower pressure than atmospheric inducing air to move into said tubular member from said pipe and mix with said gas, means for igniting the gas and air mixture for burning within said tube above the tubular member, and said tube having apertures therethrouigh for admitting limited quantities of air into said tube.

2. A pilot burner for a flare stack according to claim 1 wherein the axis of said tube converges towards the axis of the flare stack to direct the flame of the burning fuel over the upper end of said stack.

3. A pilot type burner for a flare stack according to claim 1 wherein the axis of said tube converges at an angle about twenty-seven degrees with respect to the axis of the stack and the end surface of said tube is in substantially the plane of the upper end of the stack.

References Cited by the Examiner UNITED STATES PATENTS 329,776 11/1'885 Robertson et al 158-109 867,382 10/1907 Krieg 158-118 X 1,006,324 10/1911 Werner 158-118 X 1,830,933 11/1931 Coony 158-115 2,353,865 7/1944 Armstrong 158118 X 2,480,230 8/ 1949 Elster. 2,777,512 1/1957 Johnson et al. 158115 2,779,399 1/1957 Zink et al. 1581 15 FREDERICK L. MATTESON, JR., Primary Examiner. 

1. THE COMBINATION OF A PILOT BURNER AND A FLARE STACK COMPRISING, A FLARE STACK, A GENERALLY ERECT TUBE ADJACENT THE UPPER END OF SAID STACK, A PIPE IN COMMUNICATION WITH THE DEPENDING FROM SAID TUBE AND HAVING AN OPEN LOWER END DISPOSED BELOW THE UPPER END OF SAID STACK, A TUBULAR MEMBER WITHIN SAID TUBE PROVIDING AN ANNULAR SPACE BETWEEN THE INTERIOR OF THE TUBE AND THE EXTERIOR OF THE TUBULAR MEMBER, MEANS FOR GUIDING GAS UNDER PRESSURE INTO SAID ANNULAR SPACE,SAID TUBULAR MEMBER HAVING A PLURALITY OF CIRCUMFERENTIALLY SPACED PORTS THERETHROUGH WITH THEIR AXES CONVERGING DOWNSTREAM AND TOWARDS THE AXIS OF SAID TUBULAR MEMBER WHEREBY THE GAS JETS MOVING THERETHROUGH MINGLE PROVIDING AN ENERGY RESULTANT MOVING UPWARDLY WITHIN THE TUBULAR MEMBER PROVIDING A LOWER PRESSURE THAN ATMOSPHERIC INDUCING AIR TO MOVE INTO SAID TUBULAR MEMBER FROM SAID PIPE AND MIX WITH SAID GAS, MEANS FOR IGNITING THE GAS AND AIR MIXTURE FOR BURNING WITHIN SAID TUBE ABOVE THE TUBULAR MEMBER, AND SAID TUBE HAVING APERTURES THERETHROUGH FOR ADMITTING LIMITED QUANTITIES OF AIR INTO SAID TUBE. 